Cooling fan with tapered hub

ABSTRACT

A cooling fan includes a fan housing and a rotor received in the fan housing. The fan housing has an air inlet and an outlet opposite to the air inlet. The rotor includes a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub. The hub has an outer surface expanding along a direction parallel to a central axis of the shaft from the air inlet to the air outlet.

BACKGROUND

1. Technical Field

The present disclosure relates generally to cooling fans, and more particularly to an axial fan with a large airflow.

2. Description of Related Art

Cooling fans are commonly used in combination with heat sinks for cooling electronic components, such as CPUs. Normally, the heat sink is arranged on the electronic component to absorb heat therefrom, while the cooling fan is arranged on the heat sink to produce forced airflow flowing through the heat sink to take away the heat.

Generally, the cooling fan includes a hub and a plurality of blades extending from the hub. The hub is usually cylindrical and blocks airflow in an air inlet of the cooling fan. As a result, an air-volume and an air-pressure of the airflow in the air inlet will reduce.

What is needed is a cooling fan which can overcome the limitations described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a cooling fan in accordance to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of the cooling fan of FIG. 1.

DETAILED DESCRIPTION

Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a cooling fan 100 includes a fan housing 10 and a rotor 20 received in the hosing 10. The fan housing 10 has a cubical configuration and includes a top plate 11, a bottom plate 13, and a lateral wall 15 interconnecting the top plate 11 and the bottom plate 13. Each of the top plate 11 and the bottom plate 13 has a rectangular shape similar to each other. The top plate 11 defines a circular air inlet 110.

The bottom plate 13 defines a circular air outlet 130 corresponding to the air inlet 110 of the top plate 11.

Referring to FIG. 2, the bottom plate 13 includes a supporting plate 16 at the air outlet 130. The supporting plate 16 is connected to the bottom plate 13 by a plurality of ribs (not shown). A central tube 17 extends from the supporting plate 16. The central tube 17 receives a bearing 30 therein. The lateral wall 15 is annular and has an inner surface 150 surrounding a receiving room 18.

The rotor 20 includes a hub 21 and a plurality of rotary blades 23 connecting a circumference of the hub 21. The hub 21 includes a circular top wall 210 and an annular wall 212 extending downwards from the top wall 210. The top wall 210 and the annular wall 212 cooperatively define a space 215 in the hub 21. The top wall 210 is flat and faces the air inlet 110. The rotor 20 includes a shaft 214 mounted with the hub 21. A top end of the shaft 214 is fixedly engaged in a central portion of the top wall 210 of the hub 21. The shaft 214 is assembled in the bearing 30 and rotatably mounted on the supporting plate 16. The inner surface 150 of the lateral wall 15 is parallel to a central axis O of the shaft 214.

The annular wall 212 of the hub 21 has an outer surface 218. The outer surface 218 converges (tapers) in an upward direction, i.e., the outer surface 218 of annular wall 212 slants towards the central axis O of the shaft 214 from the air outlet 130 of the bottom plate 13 to the air inlet 110 of the top plate 11. Put another way, a distance between the outer surface 218 of the hub 21 and the shaft 214 expands gradually in the downward direction along the air inlet 110 of the top plate 11 to the air outlet 130 of the bottom plate 13. Accordingly, the air inlet 110 of the top plate 11 is larger than the air outlet 130 of the bottom plate 13. The annular wall 212 of the hub 21 has an inner surface facing the shaft 214, the inner surface defines a cylinder having a constant diameter. The hub 21 receives a magnet 25 attached on the inner surface of the annular wall 212. A stator 50 surrounds the central tube 17 in the space 215.

During operation, the rotor 20 is rotated by the interaction of the alternating magnetic field established by the stator 50 and the magnetic field of the magnet 25. The rotary blades 23 thus produce forced airflow to take away heat generated in an application environment that employs the cooling fan 100. Since the outer surface 218 of the hub 21 tapers upwards to make the air inlet 110 of the top plate 11 larger than the air outlet 130 of the bottom plate 13, during rotation of the rotor 20, a block of the hub 21 for the forced airflow reduces, and the cooling fan 100 can produce larger air-volume and air-pressure in the inlet 110. Thus cooling fan 100 can operate smoothly and quietly, and the quality of the cooling fan 100 obtained should be good. In this embodiment, the cooling fan 10 can increase 5% air-volume and 48% air-pressure than a conventional fan without variable outer wall of a hub.

It is to be understood, however, that even though numerous characteristics and advantages of certain embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A cooling fan comprising: a fan housing having an air inlet and an outlet opposite to the air inlet; a rotor received in the fan housing, the rotor comprising a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub, the hub having an outer surface expanding outwards along a direction parallel to a central axis of the shaft from the air inlet to the air outlet.
 2. The cooling fan of claim 1, wherein a distance between the outer surface of the hub and the shaft gradually increases from the air inlet to the air outlet.
 3. The cooling fan of claim 1, wherein the fan housing has a lateral wall with an inner surface facing the hub, the inner surface being parallel to the central axis of the shaft.
 4. The cooling fan of claim 1, wherein the hub comprises a circular top wall and an annular wall extending from the top wall towards the air outlet, an outer surface of the circular top wall of the hub facing the air inlet being flat, an outer surface of the annular wall of the hub expanding from the air inlet to the air outlet.
 5. The cooling fan of claim 4, wherein the annular wall of the hub has an inner surface facing the shaft, the inner surface defining a cylinder having a constant diameter.
 6. The cooling fan of claim 5, wherein the hub receives a stator therein, and a magnet is attached on the inner surface of the annular wall and surrounding the stator.
 7. A cooling fan comprising: a fan housing having an air inlet and an outlet opposite to the air inlet; a rotor received in the fan housing, the rotor comprising a shaft, a hub engaged with the shaft, and a plurality of rotary blades extending outwardly from the hub, the hub having an outer surface tapered from the air outlet to the air inlet.
 8. The cooling fan of claim 7, wherein a distance between the outer surface of the hub and the shaft gradually increases from the air inlet to the air outlet.
 9. The cooling fan of claim 7, wherein the fan housing has a lateral wall with an inner surface confronting the hub, the inner surface being parallel to a central axis of the shaft.
 10. The cooling fan of claim 7, wherein the hub comprises a circular top wall and an annular wall extending from the top wall towards the air outlet, an outer surface of the circular top wall of the hub facing the air inlet being flat, an outer surface of the annular wall of the hub expanding from the air inlet to the air outlet.
 11. The cooling fan of claim 10, wherein the annular wall of the hub has an inner surface facing the shaft, and the inner surface has a constant diameter.
 12. The cooling fan of claim 11, wherein the hub receives a stator therein, and a magnet is attached on the inner surface of the annular wall and surrounding the stator. 